Large-area fiber plate, radiation image pickup apparatus utilizing the same and producing method therefor

ABSTRACT

A fiber optic plate is formed by arranging, in a mutually adjacent manner, a number of individual fiber plates of a same thickness so as to provide a light guiding plane for use in a radiation image pickup apparatus. Each of the individual fiber plates is composed of a group of optical fibers having mutually parallel axes, and the lateral faces of the individual fiber plates are mutually bonded so that the axes of the optical fibers thereof become mutually parallel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fiber plate (also called fiber opticplate), a radiation image pickup apparatus, a producing method thereforand a radiation image pickup system provided with the same, and moreparticularly to a fiber plate adapted for use in a radiation imagepickup apparatus provided with conversion means for converting aradiation into light and a photoelectric converting element forconverting light into an electrical signal and adapted to guide thelight from the conversion means to the photoelectric converting element.

In the field of radiation image pickup apparatus, particularly of X-rayimage pickup apparatus for medical purpose, there has been desired anX-ray image pickup apparatus of thin type, having a large image inputarea and capable of taking X-ray moving image with a high image quality.Also for the non-destructive testing apparatus for industrial use, thereis required a thin and inexpensive X-ray image of a large area.

For such X-ray image pickup apparatus, there are proposed, for example,(1) an X-ray detecting apparatus having a fiber plate of which thefibers are inclined to prevent mutual interference of the non-lightreceiving areas of a CCD sensor thereby achieving a large area (asdisclosed in the U.S. Pat. No. 5,563,414, and (2) an X-ray detectingapparatus having a fiber plate of which thickness is given a stepdifference to prevent mutual interference of the non-light receivingareas of a CCD sensor thereby achieving a large area (as disclosed inthe U.S. Pat. No. 5,834,782).

FIG. 37 is a schematic cross-sectional view of an X-ray detectingapparatus of the above-mentioned configuration (1), composed of aphosphor 3 consisting for example of a scintillator for converting X-rayinto visible light, individual fiber plates 2A consisting of opticalfibers or the like for guiding the visible light, obtained by thephosphor 3, to an image pickup element 1, and an image pickup element 1Afor converting the visible light, guided by the individual fiber plates2A, into an electrical signal.

In this X-ray image pickup apparatus, the individual fiber plate 2A isinclined with respect to the image pickup element 1A, and, between theindividual fiber plates 2A, there is provided a process circuit or thelike for processing the electrical signal from each image pickup element1A.

FIG. 38 is a schematic perspective view of an X-ray detecting apparatusof the above-mentioned configuration (2), wherein components equivalentto those in FIG. 37 are represented by corresponding numbers. As shownin FIG. 38, the length of the fiber plate 2 is partially changed and forexample three image pickup elements are provided as a set with stepdifferences therebetween, in order to provide each image pickup elementwith a process circuit.

However, in the above-described configuration (1), the light guide(entering/emerging) plane is inclined to the axis of the optical fiber,and the individual fiber plates are so arranged that the optical axes ofthe optical fibers mutually cross. It is difficult, with suchconfiguration, to achieve compactization of the X-ray image pickupapparatus.

On the other hand, the above-described configuration (2) results in anincrease in the dimension of the X-ray image pickup apparatus. Also asthe alignment between each stepped portion and the image pickup elementrequires a high precision, the manufacturing process requires a largenumber of steps and also requires a highly precise aligning apparatus.In consideration of these facts, the configuration (2) is not practical.

Thus, the X-ray image pickup apparatuses of the conventionalconfigurations have not been satisfactory in the increase in the size ofthe image pickup apparatus, in the cost reduction thereof and in theefficiency of the manufacturing process.

SUMMARY OF THE INVENTION

In consideration of the foregoing, an object of the present invention isto provide a large-area fiber plate suitable for compactization and costreduction of the radiation image pickup apparatus and superior in theefficiency of the manufacturing process, and a radiation image pickupapparatus and a radiation image pickup system utilizing the same.

Another object of the present invention is to provide a method forproducing a fiber plate and a radiation image pickup apparatus, capableof providing a large-area fiber plate, a radiation image pickupapparatus and a radiation image pickup system in inexpensive manner.

The present invention is featured in that, in a fiber plate in whichplural individual fiber plates of a same thickness are so arranged inmutually adjacent manner as to provide a light guiding plane larger thanthat of an individual one fiber plate, each of the plural individualfiber plates is composed of a group of optical fibers having mutuallyparallel axes and the lateral faces of the plural individual fiberplates are so bonded that the axes of the optical fibers become mutuallyparallel.

In such invention, the axes of the optical fibers are preferablyparallel or inclined to the normal line to the above-mentioned lightguiding face. Also in such invention, at least either of theabove-mentioned light guiding face or the above-mentioned lateral facesis preferably a polished surface.

Also in such invention, the above-mentioned lateral faces are preferablybonded by at least either of an adhesive or a metal.

Also in such invention, the portion of above-mentioned bonding ispreferably a radiation intercepting bonded portion.

Also in such invention, the above-mentioned lateral faces preferablyinclude a face crossing the normal line to the above-mentioned lightguiding face.

The present invention is also featured in that, in a fiber plate inwhich plural individual fiber plates of a same thickness are so arrangedin mutually adjacent manner as to provide a light guiding plane largerthan that of an individual one fiber plate, each of the pluralindividual fiber plates is composed of a group of optical fibers havingaxes parallel to the normal line to the light guiding face, and thelateral faces of the plural individual fiber plates are so bonded thatthe axes of the optical fibers become mutually parallel, and the frontface and the rear face constituting the light guiding faces of the fiberplate are same in area.

In such invention, the plural individual fiber plates are preferablybonded in the mutually parallel lateral faces thereof.

Also in such invention, the above-mentioned light guiding face ispreferably a polished surface.

Also in such invention, the above-mentioned lateral face is preferably apolished face.

Also in such invention, the above-mentioned lateral faces are preferablybonded by at least either of an adhesive or a metal.

Also in such invention, the portion of above-mentioned bonding ispreferably a radiation intercepting bonded portion.

Also in such invention, the above-mentioned lateral faces preferablyinclude a face crossing the normal line to the above-mentioned lightguiding face.

The present invention is further featured in that, in a radiation imagepickup apparatus provided with a wavelength converting member forconverting radiation into light, a photoelectric converting element forconverting light into an electrical signal and a fiber plate positionedbetween the wavelength converting member and photoelectric convertingelement, the fiber plate are composed of plural individual fiber platesof a same thickness so arranged in mutually adjacent manner as toprovide a light guiding plane larger than that of an individual onefiber plate, wherein each of the plural individual fiber plates iscomposed of a group of optical fibers having mutually parallel axes, andthe lateral faces of the plural individual fiber plates are so bondedthat the axes of the optical fibers become mutually parallel.

In such invention, the axes of the optical fibers are preferablyparallel or inclined to the normal line to the above-mentioned lightguiding face.

Also in such invention, at least either of the above-mentioned lightguiding face or the above-mentioned lateral faces is preferably apolished surface.

Also in such invention, the above-mentioned lateral faces are preferablybonded by at least either of an adhesive or a metal.

Also in such invention, the portion of above-mentioned bonding ispreferably a radiation intercepting bonded portion.

Also in such invention, the above-mentioned lateral faces preferablyinclude a face crossing the normal line to the above-mentioned lightguiding face.

Also in such invention, the width of the gap between the adjacentindividual fiber plates is preferably smaller than the width of thepixel of the photoelectric converting element.

Also in such invention, it is preferable that the photoelectricconverting element has plural pixels of mutually differentlight-receiving areas and that the width of the gap between the adjacentindividual fiber plate is smaller than the width of a pixel having thesmallest light-receiving area of the photoelectric converting element.

Also in such invention, the gap between the adjacent individual fiberplates is preferably positioned on the gap of chips constituting thephotoelectric converting element.

Also in such invention, the gap between the adjacent individual fiberplates is preferably positioned on the effective pixel area of chipsconstituting the photoelectric converting element.

Also in such invention, the joint line formed by the gaps of theadjacent individual fiber plates crosses the joint line formed by thegaps of the chips constituting the photoelectric converting element withan angle larger than 0° and smaller than 90°.

The present invention is further featured in that, in a radiation imagepickup apparatus provided with a wavelength converting member forconverting radiation into light, a photoelectric converting element forconverting light into an electrical signal and a fiber plate positionedbetween the wavelength converting member and photoelectric convertingelement, the fiber plate are composed of plural individual fiber platesof a same thickness so arranged in mutually adjacent manner as toprovide a light guiding plane larger than that of an individual onefiber plate, wherein each of the plural individual fiber plates iscomposed of a group of optical fibers having axes parallel to the normalline to the above-mentioned light guiding plane;

the lateral faces of the plural individual fiber plates are so bondedthat the axes of the optical fibers become mutually parallel, and

the front surface and the rear surface constituting the light guidingplanes of the fiber plate have a same area.

In such invention, the above-mentioned lateral faces are preferablypolished faces.

Also in such invention, the above-mentioned light guiding faces arepreferably polished faces.

Also in such invention, the above-mentioned lateral faces are mutuallybonded by at least either of an adhesive or a metal.

Also in such invention, the portion of above-mentioned bonding ispreferably a radiation intercepting bonded portion.

Also in such invention, the above-mentioned lateral faces preferablyinclude a face crossing the normal line to the above-mentioned lightguiding face.

Also in such invention, the width of the gap between the adjacentindividual fiber plates is preferably smaller than the width of thepixel of the photoelectric converting element.

Also in such invention, it is preferable that the photoelectricconverting element has plural pixels of mutually differentlight-receiving areas and that the width of the gap between the adjacentindividual fiber plate is smaller than the width of a pixel having thesmallest light-receiving area of the photoelectric converting element.

Also in such invention, the gap between the adjacent individual fiberplates is preferably positioned on the gap of chips constituting thephotoelectric converting element.

Also in such invention, the gap between the adjacent individual fiberplates is preferably positioned on the effective pixel area of chipsconstituting the photoelectric converting element.

Also in such invention, the joint line formed by the gaps of theadjacent individual fiber plates crosses the joint line formed by thegaps of the chips constituting the photoelectric converting element withan angle larger than 0° and smaller than 90°.

The present invention is further featured in that, in a radiation imagepickup apparatus consisting of an array of a plurality of radiationimage pickup units, each provided with a wavelength converting memberfor converting radiation into light, a photoelectric converting elementchip for converting light into an electrical signal and a fiber platepositioned between the wavelength converting member and photoelectricconverting element, the lateral faces of the plural individual fiberplates of the plural radiation image pickup units are so bonded that theaxes of the optical fibers become mutually parallel.

In such invention, the above-mentioned lateral faces are preferablypolished surfaces.

Also in such invention, the above-mentioned light guiding face ispreferably a polished face.

Also in such invention, in the above-mentioned radiation image pickupunit, the wavelength converting member, the photoelectric convertingelement chip and the individual fiber plate have a substantially samesize.

The present invention is further featured by a method for producing afiber plate, comprising:

a step of preparing plural individual fiber plates of a same thickness,each consisting of a group of optical fibers having mutually parallelaxes;

a step of arranging the plural individual fiber plates in such adjacentmanner as to provide a light guiding face larger in area than the lightguiding face of each individual one fiber plate; and

a step of so bonding the lateral faces of the plural individual fiberplates that the axes of the optical fibers become mutually parallel.

In such invention, the method preferably comprises:

a step of bonding at least two of the plural individual fiber platesthereby forming a set of individual fiber plates; and

a step of further bonding plural sets of the individual fiber platesthereby forming the above-mentioned fiber plate.

Also in such invention, it is preferable to polish lateral faces of theset of the individual fiber plates and then to bond the plural sets ofthe individual fiber plates in such a manner that the lateral faces aremutually adjacent.

Also in such invention, the lateral faces of the adjacent individualfiber plates are bonded with a metal or an adhesive.

Also in such invention, the surfaces of the plural individual fiberplates are preferably poslished after the fiber plates are bonded.

Also in such invention, the method preferably comprises:

a step of preparing plural individual fiber plates of a same thickness,each consisting of a group of optical fibers having axes parallel to thenormal line to the light guiding face;

a step of arranging the plural individual fiber plates in such adjacentmanner as to provide a light guiding face larger in area than the lightguiding face of each individual one fiber plate; and

a step of so bonding the lateral faces of the plural individual fiberplates that the axes of the optical fibers become mutually parallel.

Also in such invention, the method preferably comprises:

a step of bonding at least two of the plural individual fiber platesthereby forming a set of individual fiber plates; and

a step of further bonding plural sets of the individual fiber platesthereby forming the above-mentioned fiber plate.

Also in such invention, it is preferable to polish lateral faces of theset of the individual fiber plates and then to bond the plural sets ofthe individual fiber plates in such a manner that the lateral faces aremutually adjacent.

Also in such invention, the lateral faces of the adjacent individualfiber plates are bonded with a metal or an adhesive.

Also in such invention, the surfaces of the plural individual fiberplates are preferably poslished after the fiber plates are bonded.

Also in such invention, the method preferably comprises:

a step of preparing plural individual fiber plates each consisting of agroup of optical fibers having mutually parallel axes;

a step of arranging the plural individual fiber plates in such adjacentmanner as to provide a light guiding face larger in area than the lightguiding face of each individual one fiber plate; and

a step of bonding the lateral faces of the plural individual fiberplates and then polishing the surfaces of the fiber plates.

The present invention is further featured by a method for producing aradiation image pickup apparatus comprising:

a step of preparing the above-described fiber plate; and

a step of bonding to the photoelectric converting element.

In such invention, it is preferable, after the bonding of the fiberplate with planarized surfaces and the photoelectric converting element,to bond the sheet-shaped wavelength converting member to the fiberplate.

Also in such invention, it is preferable, after the bonding of the fiberplate with planarized surfaces and the sheet-shaped wavelengthconverting member, to bond the photoelectric converting element thereto.

The present invention is further featured by a radiation image pickupsystem comprising:

signal processing means for processing a signal from the above-mentionedradiation image pickup apparatus;

recording means for recording the signal from the signal processingmeans;

display means for displaying the signal from the signal processingmeans; and

a radiation source for generating the radiation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a fiber plate of the presentinvention;

FIG. 2 is a schematic view showing the configuration of a radiationimage pickup apparatus of the present invention;

FIG. 3 is a schematic cross-sectional view of an X-ray image pickupapparatus constituting an embodiment of the present invention;

FIG. 4 is a schematic plan view of image pickup elements to be employedin the present invention;

FIGS. 5A and 5B are schematic views showing the configuration in thevicinity of external connection terminals of the image pickup elements;

FIG. 6 is a schematic view showing the configuration in the vicinity ofexternal connection terminals of the image pickup elements;

FIGS. 7A and 7B are schematic views showing the configuration betweenadjacent image pickup elements;

FIGS. 8A, 8B, 8C, 8D, 8E and 8F are schematic views showing a method forproducing an image pickup apparatus;

FIGS. 9A, 9B, 9C and 9D are schematic views showing a method forproducing an image pickup apparatus of the present invention;

FIGS. 10A, 10B, 10C and 10D are schematic views showing a method forproducing a fiber plate of the present invention;

FIGS. 11A and 11B are schematic views showing another example of themethod for producing the fiber plate of the present invention;

FIG. 12 is a schematic view showing the configuration of the fiber plateconstituting an embodiment of the present invention;

FIGS. 13A, 13B and 13C are schematic views showing a method forproducing the fiber plate shown in FIG. 12;

FIG. 14 is a schematic cross-sectional view of a fiber plate of anotherembodiment of the present invention;

FIGS. 15A, 15B and 15C are schematic views showing a method forproducing the fiber plate shown in FIG. 14;

FIG. 16 is a schematic cross-sectional view of a fiber plate of stillanother embodiment of the present invention;

FIGS. 17A, 17B, 17C, 17D and 17E are schematic views showing a methodfor producing the fiber plate shown in FIG. 16;

FIG. 18 is a schematic plan view of an X-ray image pickup apparatusconstituting another embodiment of the present invention;

FIG. 19 is a schematic cross-sectional view of the X-ray image pickupapparatus shown in FIG. 18;

FIG. 20 is a schematic plan view of an X-ray image pickup apparatusconstituting still another embodiment of the present invention;

FIG. 21 is a schematic cross-sectional view of the X-ray image pickupapparatus shown in FIG. 20;

FIG. 22 is a schematic plan view of an X-ray image pickup apparatusconstituting another embodiment of the present invention;

FIG. 23 is a schematic plan view of an X-ray image pickup apparatusconstituting still another embodiment of the present invention;

FIG. 24 is a schematic cross-sectional view of the X-ray image pickupapparatus shown in FIG. 23;

FIGS. 25, 26, 27 and 28 are schematic cross-sectional views of X-rayimage pickup apparatuses constituting still another embodiments of thepresent invention;

FIG. 29 is a schematic cross-sectional view showing the relationshipbetween a pixel of the image pickup apparatus and a joint portion of thefiber plate in the present invention;

FIG. 30 is a schematic cross-sectional view of an X-ray image pickupapparatus constituting still another embodiment of the presentinvention;

FIGS. 31A, 31B, 31C and 31D are schematic views showing a methodproducing a radiation image pickup apparatus in an embodiment of thepresent invention;

FIGS. 32A, 32B, 32C, 32D and 32E are schematic views showing a methodproducing a radiation image pickup apparatus in another embodiment ofthe present invention;

FIGS. 33A, 33B, 33C, 33D, 33E and 33F are schematic views showing amethod producing a fiber plate in an embodiment of the presentinvention;

FIG. 34 is a schematic plan view of a radiation image pickup apparatusin another embodiment of the present invention;

FIG. 35 is a schematic view showing the configuration of anon-destructive testing system provided with an X-ray image pickupapparatus of the present invention;

FIG. 36 is a schematic view showing the configuration of an X-raydiagnostic system provided with an X-ray image pickup apparatus of thepresent invention;

FIG. 37 is a schematic cross-sectional view of an image pickup apparatusemploying a conventional large-area fiber plate; and

FIG. 38 is a schematic cross-sectional view of an image pickup apparatusemploying another conventional large-area fiber plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now the present invention will be clarified in detail with reference tothe accompanying drawings.

FIG. 1 is a schematic perspective view showing the basic configurationof a fiber plate of the present invention;

A single (individual or discrete) fiber plate 2 is composed of pluraloptical fibers, and a bonding material 7 bonds at least two adjacentindividual fiber plates.

The individual fiber plate to be employed in the present invention canbe obtained, for example, by forming an integral parallel bundle of1,000 to 10 million optical fibers of a diameter of 1 to 100 μm andcutting such bundle into a plate of a thickness of 1 to 20 mm in suchmanner that a plane perpendicular to the axes of the optical fiber isexposed. Therefore, taking the light guiding plane (light entering andemerging faces) of the individual fiber plate at x-y plane, the axes ofall the optical fibers are approximately parallel to the z-axis and areparallel to the normal line to the light entrance/exit faces within atolerance of about ±1°, thus forming an angle of 0°±1°.

Plural individual fiber plates of a same thickness are arranged alongthe x-y plane in such a manner that the light entrance/exit planebecomes coplanar and the lateral faces of the individual fiber platesare so bonded that the axes of the optical fibers become mutuallyparallel, whereby the fiber plates constitute a large-area fiber plateproviding a large-area light entrance/exit plane. The thicknesses ofthese fiber plates need not be exactly same but can have a certaintolerance.

In another form, the large-area fiber plate can also be produced bypreparing plural individual fiber plates of a parallelogramcross-section having axis of the optical fibers inclined to the x-yplane and bonding the lateral faces of such fiber plates in such amanner that the axes become mutually parallel.

Though only two individual fiber plates are illustrated, the numberthereof is not particularly limited. Also the thickness of theindividual fiber plates need not be exactly equal but can have a certaintolerance. It is also preferable, if necessary, to polish the surface ofthe fiber plate 2 after the mutual bonding of the individual fiberplates 2A.

The optical fiber can be composed of a known material such as glass, andpreferably of a light transmitting material such as lead-containingglass, containing a radiation intercepting material such as lead.

The bonding material can be composed of an organic or inorganic bondingmaterial as will be explained later. Particularly preferred is amaterial equal or close, in the characteristics such as thermalexpansion coefficient, to the fiber plate.

The size of the individual fiber plate is not particularly limited andcan be, for example, several tens to several thousands squarecentimeters.

FIG. 2 is a schematic view showing the basic configuration of aradiation image pickup apparatus employing the above-described fiberplate.

An image pickup element 1A is composed of an integrated circuit chipsuch as a CCD image sensor chip, a CMOS image sensor chip, a bipolarimage sensor chip, a CMD image sensor chip or a thin film transistorimage sensor chip, and plural image pickup elements are arranged toconstitute a large-area image pickup element (photoelectric convertingelement) 1.

Also plural individual fiber plates 2A are arranged to constitute alarge-area fiber plate 2.

A wavelength converting member 3 is a layer-structured member called ascintillator or a phosphor, composed of a gadolinium sulfur oxide suchas Gd₂O₂S(Tb) or an alkalimetal halide represented by cesium iodide suchas CsI(Tl).

It is preferred that the light guiding area of the bonded large-areafiber plate 2 is made equal to or larger than the effectivelight-receiving area of the bonded large-area image pickup element 1 andthat the area of the wavelength converting member 3 is made equal to orlarger than the light guiding area of the bonded large-area fiber plate2.

When a radiation enters the upper surface of the wavelength convertingmember 3 from above, the wavelength converting member 3 emits light ofvisible wavelength range. The fiber plate 2 positioned between thewavelength converting member 3 and the image pickup element 1 guides thelight to the light-receiving area thereof. The light entering thelight-receiving area is subjected to photoelectric conversion in eachpixel and is read as an electrical signal.

The fiber plate 2A, if composed of a radiation intercepting fiber plate,can intercept entry of the radiation into the image pickup element 1,thereby suppressing errors and noise generation in the image pickupelement.

In FIG. 2, the number of the individual fiber plates 2A is illustratedsame as that of the image pickup element chips 1A, but, in the presentinvention, they need not be mutually same and can be different.Preferably the individual fiber plates 2A are made larger in dimensionand smaller in number than the image pickup element chips 1A.

The image pickup apparatus of the present invention can beadvantageously employed in an X-ray image pickup apparatus to beexplained in the following, but such application is not restrictive andit can also be applied to a radiation image pickup apparatus fordetecting image a radiation other than X-ray, such as α-ray, β-ray orγ-ray.

[Embodiment 1]

FIG. 3 is a cross-sectional view of an X-ray image pickup apparatusconstituting an embodiment 1 of the present invention. FIG. 3 shows anapparatus provided with a phosphor (wavelength converting member) 3serving as a scintillator for converting X-ray into light of awavelength detectable by an image pickup element (photoelectricconverting element) such as visible light, an individual fiber plate 2Acomposed of plural optical fibers for guiding the light, converted bythe wavelength converting member 3, to an image pickup element, and animage pickup element 1 provided with a photoelectric convertingphotosensor for converting the light into an electrical signal.

The apparatus is further provided with an adhesive 7 for mutuallybonding the individual fiber plate 2A, and, if necessary, with anelastic transparent adhesive 6 for adhering a large-area fiber plate 2with an image pickup element 1 including plural pixels, a flexible board4 having wirings for outputting the electrical signal from each imagepickup element chip 1A to the exterior, a bump 5 for electricallyconnecting the flexible board 4 and the image pickup element chip 1A, aprinted circuit board 12 to which the flexible board 4 is connected, analuminum protective sheet 8 for protecting the phosphor 3, a basesubstrate 10 for mounting the image pickup element 1, a base casing 11for holding the base substrate 10, a casing cover 9 provided in the basecasing 11, a spacer 13 provided between the image pickup element 1 andthe fiber plate 2 for maintaining a constant gap therebetween, and afiller adhesive 14 for maintaining the transparent adhesive 6 betweenthe fiber plate 2 and the image pickup element 1.

The X-ray image pickup apparatus shown in FIG. 3 is prepared by adheringthe image pickup element 1 and the large-area fiber plate 2 providedwith the plural individual fiber plates 2A, by means of the transparentadhesive 6.

FIG. 4 is a plan view showing an example of the schematic configurationof the image pickup element employable in the present invention.

FIG. 4 shows an ordinary pixel 101 having two-dimensionally arrangedplural photosensors, plural peripheral pixels 1204 provided outside adriving circuit 103, a driving circuit 103 for driving the peripheralpixels 104 in succession, and input/output terminals 102 of the imagepickup element 1A.

The ordinary pixels 101 are arranged on the approximately entire area ofthe image pickup element chip 1A, with a pitch for example of 160 μm aswill be explained later. Between the ordinary pixels 101, the drivecircuit 103 is dividedly positioned. As the peripheral pixel 104 issmaller in area than the ordinary pixel 101, the pixel signal iscompensated to cancel the difference in the area.

FIGS. 5A and 5B show the configuration in the vicinity of the outputterminals of the image pickup element employed in the present invention.FIG. 5A is a plan view in the vicinity of a bump 5 of the image pickupelement chip 1A and the flexible wiring board 4, and FIG. 5B is across-sectional view along a line 5B in FIG. 5A.

There are shown a connecting bump 5, an inner lead 401 of the flexiblewiring board 4 to be connected to the bump 5, and an organic insulatinglayer 105 composed for example of a polyimide resin layer, forpreventing the shortcircuiting between the end of the image pickupelement chip 1A and the inner lead 401 and the end chipping of the imagepickup element 1.

FIG. 6 is a schematic view showing a method of electrical connectionbetween the bump 5 and the flexible circuit board 4 shown in FIGS. 5Aand 5B.

At first, for example a polyimide resin layer is formed as the organicinsulating layer 105, with a thickness of 25 μm, at an end of the imagepickup element chip 1A.

Then for forming electrical connection between the bump 5 and theflexible wiring board 4, a bump 5 is formed for example by a stud bumpprocess or by plating on an input/output terminal 102 of the imagepickup element chip 1A.

Then the bump 5 and the inner lead 401 are fused for example byultrasonic bonding, whereby the metal constituting the bump 5 and themetal constituting the inner lead 401 are electrically and physicallyconnected by metal-metal bonding. As an example, the inner lead 401 canbe formed by etching a copper foil, and plating with nickel and gold toa thickness of about 18 μm, and the total thickness of the flexiblewiring board can be about 50 μm.

Then, while the image pickup element chip 1A is vertically sandwichedbetween supports 17 and 18, a jig or tool 19 is moved with respectthereto in a direction indicated by an arrow, whereby the inner lead 401is bent downwards by about 90° at the end of the image pickup element1A.

FIGS. 7A and 7B are respectively a cross-sectional view and a plan viewof the vicinity of the flexible wiring board of the image pickup elementemployed in the present invention.

As shown in FIGS. 7A and 7B, in the X-direction, the width S1 of theperipheral pixel 104 is smaller than the width S2 of the ordinary pixel101 (S1<S2).

In FIG. 7B, the pitch P2 of the peripheral pixels 104 is shown differentfrom the pitch P1 between the ordinary pixel 101 and the peripheralpixel 104, but these pitches are preferably same (P2=P1) and also equalto the picth P between the ordinary pixels (P1=P2=P).

In this manner the pixel pitch becomes same in all the peripheral pixelsand the ordinary pixels, thereby improving the image quality.

FIGS. 8A to 8F show the bonding process between the image pickup elementand the base substrate employed in the present invention. At firstplural image pickup element chips 1A provided with the flexible board 4are placed on a stage 32, utilizing an alignment camera 33 and analignment head 31 movable in the X, Y, Z and e (rotational) directions.In this state, each image pickup element chip 1A is fixed on the stage32 by suction, by an unrepresented vacuum apparatus, through a hole 32Aformed on the stage 32 (FIG. 8A).

In this state, each image pickup element chip 1A is inspected for therequired function. More specifically, an inspection jig 34 is used toinspect whether the image pickup element chip 1A has been damaged forexample by electrostatic charge (FIG. 8).

If a defect is found in the image pickup element chip 1A in theinspection, the vacuum apparatus below such chip is turned off and thedefective chip is replaced by the alignment head 31 (FIG. 8C).

Then adhesive 35 such as UV curable resin or silicone resin is coated byan adhesive dispenser 34 onto the upper face of the image pickup elementchip 1A (FIG. 8D).

Then the flexible wiring board 4 is inserted into an elongated hole 10Aprovided in the base substrate 10, which is then brought into contactwith the image pickup element 1 and the adhesive is set for fixation byUV irradiation or by pressurizing (FIG. 6E).

It is advantageous to match the size of the individual fiber plate 2Awith that of the image pickup element chip 1A and to mutually align thetwo. Also the base substrate 10 is preferably composed of glass orpermalloy (iron+nickel) in consideration of matching with the imagepickup element 1 in thermal expansion coefficient etc.

After the fixation by bonding of the image pickup element 1 and the basesubstrate 10, the vacuum apparatus is turned off and the image pickupelement 1 and the base substrate 10 are removed from the jig 36 such asthe stage (FIG. 8F).

In this manner there can be obtained the large-area image pickup element1 by bonding plural image pickup element chips 1A.

FIGS. 9A to 9D are schematic views showing steps of adhering thelarge-area image pickup element employed in the present invention andthe aforementioned large-area fiber plate, wherein FIGS. 9A and 9C arecross-sectional views and FIGS. 9B and 9D are plan views.

On each image pickup element chip 1A adhered to the base substrate 10, aspacer 13 is positioned in order to maintain the gap to the large-areafiber plate 2 (FIG. 9A).

The spacer 13 can be spherical or cylindrical. Then sealing material 37is coated on the image pickup element 1 and filler adhesive 14 is coatedso as to fill the gap of the image pickup elements 1 (FIG. 9B).

The sealing material 37 is provided in a part thereof with an aperture37A through which transparent adhesive 6 is filled by vacuum injectionas will be explained later. In order to prevent leakage of vacuum insuch injection, the filler adhesive 14 is filled also in the gapsbetween the image pickup element chips 1A on the upper surface of thebase substrate 10.

Then the large-area fiber plate 3 is adhered onto the large-area imagepickup element 1, across the spacer 13 (FIG. 9C). Also if necessary,there is preferred a configuration in which the adhesive 7, used formutual bonding of the fiber plates 2, is positioned directly above thegap between the image pickup element chips 1A or between the pixels.

Then pressing or pressing under heating is executed to maintain auniform gap between the image pickup element chip 1A and the fiber plateand to set the sealing material 37. Then, in a vacuum chamber, the gapbetween the large-area fiber plate 2 and the image pickup element 1 ismaintained under a reduced pressure, and a port (not shown) containingthe transparent adhesive 6 is attached to the aperture 37A, and thepressure is returned to the atmospheric pressure whereby the transparentadhesive is filled into the gap between the fiber plate 2 and the imagepickup element 1.

Then the aperture 37A is sealed with a sealant 38 (FIG. 9D).

Then the sheet-shaped wavelength converting member 3 is adhered onto thefiber plate 2 thereby completing the X-ray image pickup apparatus.

The wavelength converting member 3 may also be formed by evaporating thematerial thereof or coating a mixture of powdered phosphor and a binderon the fiber plate 2, and, in such case, the wavelength convertingmember 3 is provided on the fiber plate 2 prior to the step shown inFIG. 9C.

Now reference is made again to FIG. 3 for explaining the function of theX-ray image pickup apparatus. An unrepresented X-ray source is providedat the side of the wavelength converting member 3 and X-ray isirradiated from the X-ray source in a state where an object ispositioned between the X-ray source and the X-ray image pickupapparatus. The X-ray irradiates the object, and is transmitted with theRoentgen information having a difference in the intensity, generated intransmitting the object, to the X-ray image pickup apparatus.

In the X-ray image pickup apparatus, the wavelength converting member 3converts the X-ray into light such as visible light, corresponding tothe intensity of the X-ray. The light obtained by such conversion istransmitted through the fiber plate 2 to the image pickup element 1.Since the fiber plate 2 and the image pickup element 1 are mutuallyadhered by the transparent adhesive 6, the light enters the image pickupelement 1 without attenuation in passing the transparent adhesive 6.

The light also enters the adhesive 7 and is absorbed or reflecctedtherein, thereby lowering the light transmittance. Such light willgenerate a line defect if it enters the pixel of the image pickupelement 1, but, by selecting the individual fiber plate 2A and the imagepickup element chip 1A of a same size and mutually aligning the two,there can be obtained a configuration in which the light from theadhesive 7 does not affect much the pixel of the image pickup element 1.

The image pickup element chip 1A converts the entering light into anelectrical signal corresponding to the light intensity. Such electricalsignal is read out, through the bump 6, to the lead 401 of the flexiblewiring board 4, in response to an instruction of an unrepresentedreadout circuit. The electrical signal read out to the flexible wiringboard 4 is supplied to an external circuit formed on a printed circuitboard 12 for A/D conversion followed by image processing.

(Producing Method for Large-Area Fiber Plate)

In the following there will be explained a method for producing thelarge-area fiber plate to be employed in the present invention.

FIGS. 10A to 10D are schematic views showing an example of the producingmethod for the large-area fiber plate employed in the present invention.

At first, two individual fiber plates 2A are mutually bonded byadhesive, as shown in FIG. 10A. In such operation, the individual fiberplates are often bonded with a slight mutual displacement as shown inFIG. 10A, even if the bonding is executed carefully. If all theindividual fiber plates 2A are bonded in this manner, there will resultan unnecessarily large gap. In this producing method, in order to avoidsuch unnecessarily large gap, at least a lateral face of the fiberplates 2 bonded with mutual displacement is polished to a broken-linedportion 41 to obtain an aligned flat lateral face 2B as shown in FIG.10B.

Then another set of the two individual fiber plates 2A is prepared by aprocedure similar to that shown in FIGS. 10A and 10B, and such two setsof the fiber plates are bonded in such a manner that the respective flatpolished lateral faces 2B mutually abut (FIG. 10C).

Then, if necessary one of the remaining four lateral faces is polishedto a broken line 41. Also the remaining three lateral faces may bepolished as shown in FIG. 10D to reduce the gap between the adjacentlateral faces there obtaining a large-area fiber plate of which all thefour lateral faces are flat.

In the foregoing there has been explained an example of bonding fourindividual fiber plates 2A to obtain a large-area fiber plate 2, but, inpractice, there are bonded a predetermined number of the individualfiber plates 2A in order to obtain the fiber plate 2 of a desired size.

FIGS. 11A and 11B are schematic cross-sectional views showing anotherproducing method for the fiber plate to be employed in the presentinvention. Now there will be explained an example of producing thelarge-area fiber plate 2 by bonding six fiber plates 2A, but FIGS. 11Aand 11B show only three individual fiber plates 2A therein. In practice,there are bonded the fiber plates 2A of a predetermined number in orderto obtain the large-area fiber plate 2 of a desired size.

In the cross section of the large-area fiber plate 2 obtained by themethod shown in FIGS. 10A to 10D, a chipped portion 43 as shown in FIG.11A is generated at the corner in the polishing operation of the lateralface or in the handling in different steps. Therefore, the front andrear surfaces constituting the light guiding faces of the large-areafiber plate after bonding are polished until such chipped portion 43 isremoved, thereby providing the large-area fiber plate 2 without thechipped portion as shown in FIG. 11B.

The large-area fiber plate 2 thus obtained and shown in FIG. 11B isadhered to the large-area image pickup element 1 across the spacer 13 ifnecessary.

[Embodiment 2]

FIG. 12 is a cross-sectional view of a large-area fiber plate 2 of anembodiment 2 of the present invention.

The large-area fiber plate 2 shown in FIG. 12 is featured by employing,as the adhesive 7, an adhesive material composed of for example epoxyresin and containing an X-ray interrupting member 7A such as lead.

Examples of the adhesive include ethylene-vinyl acetate copolymer,carboxyl-denatured ethylene-vinyl acetate copolymer,ethylene-isobutylacrylate copolymer, polyamide, polyester, polymethylmethacrylate, polyvinylether, polyvinylbutyral, polyurethane,styrene-butylene-styrene (SBS) copolymer, carboxyl-denatured SBScopolymer, styrene-isoprene-styrene (SIS) copolymer,styrene-ethylene-butylene-styrene (SEBS) copolymer, maleicacid-denatured SEBS copolymer, polybutadiene rubber, chloroprene rubber(CR), carboxyl-denatured CR, styrene-butadiene rubber,isobutylene-isoprene copolymer, acrylonitrile-butadiene rubber (NBR),carboxyl-denatured NBR, epoxy resin, silicone rubber (SR) and mixturesthereof.

Also if necessary there may be added, as an auxiliary reactant or acrosslinking agent, phenolic resin, polyols, isocyanates, melamineresin, urea resin, urotropine resin, amines, acid anhydrides, peroxides,metal oxides, organic acid metal salts such as chromiumtrifluoroacetate, alkoxides of titanium, zirconia, aluminum etc.,organometallic compounds such as dibutyl tin dioxide, photoinitiatorssuch as 2,2-diethoxyacetophenone or benzyl, sensitizers such as amines,phosphor compounds, chlorine compounds etc., a hardening agent, avulcanizing agent, a controlling agent, an antideterioration agent, aheat resistance improving agent, a thermal conduction improving agent, asoftening agent, a coloring agent, various coupling agents, or a metaldeactivating agent.

As the intercepting member 7A, there is employed at least a metalselected from iron, cobalt, nickel, copper, zinc, silver, tin,gadrinium, tungsten, platinum, gold, lead and bismuth, or an alloycontaining such metal or a compound of such metal. Such metal, alloy ofcompound may be used in combination with lead-containing solder pastesuch as Pb—Sn, lead-free solder paste or silver paste. Otherwise suchmetal, alloy or compound may be used in a particular form, and, in suchcase, there may also be employed an inorganic or organic particle(carbon particle or plastic ball) with a coating formed by plating orsputtering.

The large-area fiber plate of the present embodiment can preventunhindered transmission of the radiation through the joint portion ofthe individual fiber plates, since such joint portion is composed of theradiation intercepting adhesive.

The X-ray image pickup apparatus utilizing such large-area fiber platecan prevent entry of the X-ray, entering the wavelength convertingmember 3 and not converted into the light therein, into the image pickupelement 1. More specifically, the X-ray, entering the wavelengthconverting member 3 and not converted into the light, is intercepted bythe material itself, containing lead or the like, of the large-areafiber plate 2 and/or the intercepting adhesive 7. It is thus madepossible to suppress the noise generation caused by the X-ray entry intothe image pickup element 1.

FIGS. 13A to 13C are schematic views showing a producing method for thelarge-area fiber plate shown in FIG. 12.

At first, as shown in FIG. 13A, the adhesive and the X-ray interceptingmember 7A are agitated for example with a stirring rod. After the foamsgenerated by agitation are removed, the bonding material consisting ofthe adhesive containing the X-ray intercepting member 7A is filled intothe gap between the fiber plates by a dispenser 46 or by screen printing(FIG. 13B). The filling operation is preferably executed under a reducedpressure in order to facilitate escaping of the air in the gap.

Then the adhesive is set under mutual pressurizing of the individualfiber plates 2A. The setting can be achieved by UV irradiation or byheating within a range from the room temperature to 200° C. Thereafterthe adhesive overflowing on the upper surface of the fiber plate 2 isscraped off (FIG. 13C). In this manner there can be obtained alarge-area fiber plate 2.

[Embodiment 3]

FIG. 14 is a schematic cross-sectional view of a large-area fiber plateof an embodiment 3 of the present invention. In this embodiment, thelarge-area fiber plate 2 is prepared by bonding the individual fiberplates 2A with a low melting metal (having a melting point not exceeding330° C.) and liquid flux.

The low melting metal to be employed in the present invention can be analloy containing at least two of the metals such as Pb, Sn, Bi, Sb, In,Ag, Cd etc. for example cocrystalline solder such as Sn—Pb (63:37 wt. %)or high melting solder such as Sn—Pb (10:90 wt. %). Also the low meltingmetal is desirably in particular form for easy mixing with the liquidflux.

Also as the liquid flux, there can be employed a liquid flux containinga resin component such as purified rosin, hydrogenated rosin orpolymerized rosin and a solvent component for example an alcohol such asterpineol, 1,4-butanediol or methyl cellosolve or a ketone such asmethylethylketone, methylisoproopylketone or methylisobutylketone as theessential components, and further suitably containing other additivesfor example a viscosity regulating agent such as polyethylene glycol,polyvinyl butyral or petroleum resin and an active agent such as maronicacid, succinic acid or triethanolamine.

Also there can be employed an aqueous liquid flux containing apolyhydric alcohol component such as polyethylene glycol, glycerin orpolyvinyl alcohol and water which is a solvent component, as theessential components, and further suitably containing additives forexample a viscosity regulating agent such as polyacrylamide, and anactive agent such as an organic acid, an organic or inorganic halide,diethylamine hydrochloric acid salt. Particularly preferred is aqueousliquid flux.

FIGS. 15A to 15C are schematic views showing a producing method for thelarge-area fiber plate shown in FIG. 14.

At first, as shown in FIG. 15A, the powdered low melting metal 48 andthe liquid flux 47 are mixed. After the foams generated by agitation areremoved, the liquid flux 47 containing the X-ray intercepting lowmelting metal 48 is filled into the gap between the fiber plates by adispenser or by screen printing (FIG. 15B). The filling operation ispreferably executed under a reduced pressure in order to facilitateescaping of the air in the gap.

Then the individual fiber plates 2A are mutually pressed and the lowmelting metal 48 is fused at the same time by heating at a temperatureexceeding the melting point. Thereafter the low melting metal 48eventually overflowing on the upper surface of the fiber plate 2 isscraped off. In this manner there can be obtained a large-area fiberplate 2 (FIG. 15C).

[Embodiment 4]

FIG. 16 is a schematic cross-sectional view of a large-area fiber plateof an embodiment 4 of the present invention. In this embodiment, thelarge-area fiber plate 2 is prepared by bonding the individual fiberplates 2A with a first metal layer 49 and a second metal layer 50.

FIGS. 17A to 17C are schematic views showing a producing method for thelarge-area fiber plate shown in FIG. 16.

At first both surfaces of the individual fiber plate 2A are coated withacid etching resist 51 such as a photosensitive film resist (FIG. 17A).

Then the resist 51 is closely adhered, by heating, to the fiber plate2A. Then, in order to improve adhesion of the glass with the first metallayer 49 to be explained later, the end face of the fiber plate 2 isetched with fluoric acid, potassium fluoride or acidic ammonium fluorideto form a coarse surface 52 (FIG. 17B).

Then, on the etched end face (coarse surface 52), a first metal layer 49for example of nickel or copper is formed by electroless plating (FIG.17C).

Then, on the first metal layer 49, a second metal layer 50 composed ofan alloy of low melting metals is formed by electroplating (FIG. 17D).It is difficult to plate the second metal layer 50 on an insulatingmaterial such as glass. For this reason the above-mentioned first metallayer 49 is provided at first to form a conductive substrate and thesecond metal layer 50 is then formed by electroplating.

Then, after the resist 51 is peeled off, the individual fiber plates 2Aare mutually pressed and the second metal layer 50 is heated at atemperature exceeding the melting point but not exceeding 330° C. (FIG.17E).

Thereafter the first and second metal layers 49, 50 eventuallyoverflowing on the upper surface of the fiber plate 2 is scraped off. Inthis manner there can be obtained a large-area fiber plate.

In the second to fourth embodiments, as explained in the foregoing, thefiber plates 2A are mutually connected with the bonding material 7 withX-ray intercepting property. Thus, by employing the large-area fiberplate of these embodiments in the radiation image pickup apparatus asshown in FIGS. 2 and 3, the X-ray not converted into light by thewavelength converting member 3 and emitted toward the fiber plate isintercepted by the base member of the fiber plate. In this manner theimage pickup element 1 can be shielded from X-ray and there can besuppressed the noise generation.

[Embodiment 5]

FIGS. 18 and 19 are respectively a plan view and a cross-sectional viewof an embodiment of the X-ray image pickup apparatus of the presentinvention.

The basic configuration is same as that of the image pickup apparatusshown in FIGS. 2 and 3, except that the large-area fiber plate 2 and thelarge-area image pickup element 1 are adhered with mutual alignment insuch a manner that a joint line formed by the bonding portions 7 of theindividual fiber plates 2A is positioned above the gaps of the imagepickup element chips 1A. More specifically, the width of the joint lineconsisting of the bonding portions 7 is made smaller than the gapbetween the image pickup element chips 1A so that the joint line doesnot cover the pixel areas even in the presence of a slight positionaldisplacement.

The bonding material employed in the bonding portion 7 is preferablycomposed of a material equal to or same as the fiber plate in thecharacteristics such as thermal expansion coefficient. In the presentembodiment, the bonding material can be transparent or opaque since thejoint of the fiber plates is aligned with that of the image pickupelements.

[Embodiment 6]

FIGS. 20 and 21 are respectively a plan view and a cross-sectional viewshowing another embodiment of the X-ray image pickup apparatus.

In case, as shown in FIGS. 20 and 21, the joint portion 7 of the fiberplates is so positioned, with a positional displacement, as to cover theperipheral pixels 104 of the image pickup element 1, the difference inthe optical transmittance between the joint portion 7 and the fiberplate 2A results in a line defect or a pixel defect because the pixel ofthe row positioned under such joint portion 7, particularly theperipheral pixel 104, is smaller in size. A loss in sensitivity isunavoidable even in the larger ordinary pixel 101. Also the leakingX-ray, not converted into light but transmitted by the phosphor mayenter the image pickup element through the joint portion 7, therebygenerating a line-shaped shot noise with a deterioration in imagequality, and leading to deterioration of the element.

In the X-ray image pickup apparatus shown in FIGS. 18 and 19, the jointof the fiber plates is aligned with that of the image pickup elements.Such configuration prevents the light, entering from the phosphorthrough the joint of the fiber plate, from entering the pixel row of theimage pickup elements, thereby avoiding the line defect. Also theleaking X-ray from the phosphor is prevented from entering the imagepickup elements through the joint of the fiber plate, thereby avoidingline-shaped shot noise.

However, in case the number of the individual fiber plates is differentfrom that of the image pickup element chips, there is encountered asituation where the joint of the individual fiber plates cannot bematched with that of the image pickup element chips.

The following embodiment discloses a radiation image pickup apparatuscapable of avoiding line defect even in such case.

[Embodiment 7]

In the X-ray image pickup apparatus shown in FIG. 22, the joint lineconsisting of the bonding portions 7 of the individual fiber plates andthe line of the pixel row of the image pickup elements are mutuallyinclined (angle θ≠0). Such configuration allows to prevent the entry ofthe light entering through the bonding portions of the fiber plates intoall the pixels on a pixel row, thereby preventing the generation of theline defect. Even if the light from the bonding portions 7 of the fiberplates enters a part of the plural pixels arranged in a row, a defectsignal is generated only in a part of the pixels and does not form aline defect. In such configuration, the bonding material is preferablycomposed of an X-ray intercepting bonding material for examplecontaining lead, in order that the leaking X-ray from the wavelengthconverting member does not enter the image pickup elements through thebonding portions of the fiber plates.

In the above-described embodiment, the joint line of the fiber plates isinclined with respect to the pixel row of the image pickup elements inorder that the joint line of the fiber plates does not become parallelto the pixel row of the image pickup elements, but it is also possibleto adopt the following configuration.

[Embodiment 8]

FIGS. 23 and 24 are respectively a plan view and a cross-sectional viewof another embodiment of the X-ray image pickup apparatus of the presentinvention.

In the apparatus shown in FIGS. 23 and 24, the joint line of the fiberplates is positioned on the image pickup area of the image pickupelement 1A but between the adjacent pixel rows, in order that the lightentering from the phosphor through the joints of the bonding portions ofthe fiber plates does not enter the pixels of the image pickup element.Also, if necessary, the width of the bonding portions 7 (width of jointline) is sufficiently larger than the dimension of the ordinary pixel104 in order to avoid line defect even if the bonding portion 7 of thefiber plates is somewhat displaced from the gap between the ordinarypixels. In such configuration, the bonding material is preferablycomposed of an X-ray intercepting bonding material for examplecontaining lead, in order that the X-ray does not enter the image pickupelements through the bonding portions of the fiber plates.

In the configuration shown in FIGS. 23 and 24, there are combined alarge-area fiber plate formed by bonding 16 idividual fiber plates 2Aand a large-area image pickup element composed of nine image pickupelement chips 1A, but it is preferable to reduce the dimension of theimage pickup element chip thereby selecting the number of the imagepickup element chips larger than that of the individual fiber plates.

[Embodiment 9]

FIG. 25 is a schematic cross-sectional view of an embodiment of theX-ray image pickup apparatus of the present invention.

In the fiber plate of this apparatus, the lateral face of the individualfiber plate at the bonding portion thereof is so inclined as to crossthe normal line to the light guiding plane.

In the X-ray image pickup apparatus shown in FIG. 25, the end portion(lateral face) of the fiber plate is so formed that the leaking X-rayentering the bonding portion 7 of the fiber plates falls on the lateralface constituting the bonding portion of the fiber plates and does notenter the image pickup element. In order that the leaking X-ray passesthe lateral face constituting the bonding portion of the fiber plate,the lateral face 71 of the individual fiber plate 2A can be so formed asto be non-parallel to such leaking X-ray. In the present embodiment, thelateral face 71 of the individual fiber plate is given an inclination ofseveral degrees to several tens of degrees with respect to the normalline to the light guiding plane of the fiber plate, namely with respectto the axes of the optical fibers. In such configuration, the leakingX-ray transmitted by the wavelength converting member 3 enters the fiberplate and intercepted therein, as shown in FIG. 25. Since the X-ray doesnot enter the image pickup device through the bonding portion of thefiber plate, there can be suppressed the generation of the line-shapedshot noise. The individual fiber plate in this embodiment is composed ofa radiation intercepting fiber plate, but the bonding material need notnecessarily be composed of a radiation intercepting bonding material.

The bonding material 7 is preferably same as or similar to the fiberplate in the characteristics such as thermal expansion coefficient etc.

In the foregoing, it is assumed that all the lateral faces 71 of thefiber plate have a same inclination to the leaking X-ray, but it is alsopossible that a part of the lateral faces 71 has such inclination to theleaking X-ray.

Also the apparatus shown in FIG. 25 may have not only a configuration inwhich the axes of the optical fibers are parallel to the normal line tothe light guiding face of the individual fiber plate 2A but also aconfiguration in which the axes of the optical fibers are parallel tothe lateral face of the individual fiber plate 2A. The latterconfiguration can be realized by preparing plural individual fiberplates formed by cutting a bundle of optical fibers in inclined mannerand bonding such individual fiber plates in such a manner that the axesof the optical fibers in such fiber plates become mutually parallel. Insuch case the position of the light guiding face constituting the lightentrance face and that of the light guiding face constituting the lightexit face are mutually displaced according to the inclination angle ofthe optical fibers.

[Embodiment 10]

FIG. 26 is a schematic cross-sectional view of an embodiment of theX-ray image pickup apparatus of the present invention.

In the fiber plate of this apparatus, the lateral face constituting thebonding portion of the individual fiber plate is formed as facesinclined across a folding point, both faces crossing the normal line tothe light guiding plane.

More specifically, as shown in FIG. 26, the bonding portion 7 of thefiber plate has a chevron shape, so that a part of the lateral face 72of the fiber plate across the thickness thereof has a certaininclination to the leaking X-ray.

[Embodiment 11]

FIG. 27 is a schematic cross-sectional view of an embodiment of theX-ray image pickup apparatus of the present invention.

As shown in FIG. 27, the lateral face of the fiber plate is formed witha step, so that the bonding portion 7 of the fiber plate has a steppedstructure. In the fiber plate of this apparatus, the lateral face of theindividual fiber plate includes a face crossing the normal line to thelight guiding plane, at the above-mentioned step.

In the foregoing there have been explained examples of the shape of thelateral face (bonding portion 7) of the fiber plate to be employed inthe present invention.

In summary, the lateral face of the fiber plate to be employed in thepresent invention can have any other form than those illustrated in theforegoing, such as a zigzag shape or an arc shape, as long as theleaking X-ray entering the bonding portion 7 does not pass through theside of the fiber plate.

[Embodiment 12]

In case the bonding portion 7 of the fiber plate is positioned above theperipheral pixel of the image pickup element as shown in FIG. 20, sincethe optical transmittance of the individual fiber plate 2A is differentfrom that of the bonding portion 7 for the individual fiber plates 2A,there will result a line defect covering plural lines if the pixel rowof the image pickup element 1 is positioned under such bonding portion 7and if such bonding portion 7 has a large width. Also if the leakingX-ray, not converted into light but transmitted by the wavelengthconverting member, enters the image pickup element through the bondingportion, there will result a line-shaped shot noise, thus deterioratingthe image quality. The peripheral pixel is made smaller than theordinary pixel.

Therefore, in the present embodiment, as shown in FIGS. 28 and 29, thewidth “d” of the bonding portion 7 of the individual fiber plate is madesmaller than the width “P” of the image pickup element 1 (d<P) wherebythe line defect is limited to one line even if the pixel row of theimage pickup element is positioned under the bonding portion. Also theX-ray leaking from the wavelength converting member 3 can be interceptedby employing a bonding material composed of adhesive containing aradiation intercepting material such as lead. More preferably, the width“d” of the bonding portion 7 is made smaller than the width “a” of anaperture formed by the opaque layer of the pixel 101 (d<a). It is alsopreferred that the width “d” of the bonding portion 7 of the fiber plateis smaller than the width of the peripheral pixel 101, which is smallerthan the width of the ordinary pixel 101, namely that the width “d” ofthe bonding portion 7 of the fiber plate 2A is smaller than the minimumwidth of the pixel within the image pickup element 1. The material ofthe bonding portion is preferably same as or similar to the fiber platein characteristics such as thermal expansion coefficient.

[Embodiment 13]

FIG. 30 is a schematic cross-sectional view of an image pickup unitconstituting the X-ray image pickup apparatus in an embodiment of thepresent invention. The apparatus shown in FIG. 30 is provided withwavelength conversion means 3 for converting X-ray into light of awavelength detectable with an image pickup element such as visiblelight, a fiber plate 2A consisting of plural optical fibers for guidingthe light, converted by the wavelength conversion means 3, to an imagepickup element 1A, a transparent adhesive 6 of excellent elasticity foradhering the fiber plate 2A with an image pickup element 1A havingplural pixels 101, an image pickup element 1A having a light-receivingunit for converting the light into an electrical signal, a flexiblewiring board 4 having wirings for outputting the electrical signal ofthe image pickup element 1A to the exterior, a bump 5 for electricallyconnecting the flexible wiring board 4 with the image pickup element 1A,an aluminum protective sheet 8 for protecting the wavelength convertingmember 3, a base substrate 10 for mounting the image pickup element 1A,and a seal material 14 for maintaining the transparent adhesive 6between the fiber plate 2A and the image pickup element 1A.

A large-area image pickup apparatus may be obtained by preparing pluralimage pickup units as shown in FIG. 30 and bonding lateral faces ofneighboring fiber plates 2A so as to provide a large-area radiationreceiving surface.

FIGS. 31A to 31D are schematic views showing a producing method for theX-ray image pickup unit, wherein FIGS. 31A and 31C are cross-sectionalviews while FIGS. 31B and 31D are plan views. The lateral faces of thefiber plate 2A are polished, and the longitudinal and transversaldimensions of the fiber plate 2A are substantially equal to those of theimage pickup element 1A whereby they have approximately same areas.

The fiber plate 2A are polished on both surfaces thereof, so that thelight guiding face (light entrance/exit face) is composed of a flatpolished surface. The polishing method will be explained later.

At first the image pickup element 1A is adhered and fixed to the basesubstrate 10 with an adhesive 35. On the image taking face of the imagepickup element 1A, a spacer 13 of spherical or cylindrical shape isplaced in order to maintain the gap between the image pickup element andthe fiber plate (FIG. 31A).

Then sealing material 37 is coated on the image pickup element (FIG.31B). The seal material 37 is provided in a part thereof with anaperture 37A as shown in FIG. 31B. A pixel drive circuit 103 includesvertical shift registers and a horizontal shift register.

Then, after the fiber plate 2A on which the wavelength converting member3 is formed is positioned on the spacer 13, the fiber plate 2A and theimage pickup element 1A are mutually pressed under heating to achieveadhesion (FIG. 31C).

Then, in a vacuum chamber, the gap between each fiber plate 2A and eachimage pickup element 1A is maintained under a reduced pressure, and anunrepresented port containing the transparent adhesive is attached tothe aperture 37A, and the pressure is returned to the atmosphericpressure whereby the transparent adhesive is filled into the gap.Thereafter the aperture 37A is sealed with a sealant 38 (FIG. 31D). TheX-ray image pickup unit can be obtained in this manner.

An X-ray image pickup apparatus of a large area can be obtained byarranging and bonding plural X-ray image pickup units in such a mannerthat the X-ray receiving faces lie on a same plane.

In the example shown in FIGS. 31A to 31D, the seal material 37 isprovided only to a position which is inside the end portion of the imagepickup element chip 1A by a peripheral pixel, but it may also beprovided to the end portion as shown in FIG. 30.

In the present apparatus, the wavelength converting member 3 provided onthe light entrance surface of the fiber plate 2A by evaporation, coatingor printing, and such process is preferably executed after the polishingof the fiber plate 2. It may also be executed after the fiber plate 2Ais adhered to the image pickup element 1A.

[Embodiment 14]

FIGS. 32A to 32E are schematic views showing another producing method ofthe X-ray image pickup unit constituting an embodiment of the presentinvention, wherein FIGS. 32A, 32C and 32D are cross-sectional viewswhile FIGS. 32B and 32E are plan views.

On the image pickup element 1 a adhered with the base substrate 10, thespacer 13 is placed in order to maintain the gap between the imagepickup element 1A and the fiber plate 2A (FIG. 32A). The fiber plate 2Aused herein is in advance planarized by polishing on both surfaces.

Then sealing material 37 is coated on the image pickup element 1 (FIG.32B). The seal material 37 is provided, as shown in FIG. 32B, in a partthereof with an aperture 37A, through which transparent adhesive isfilled by a vacuum injection method as will be explained later.

Then, the fiber plate 2A is positioned on the spacer 13 and adhered(FIG. 32C). Then, in a vacuum chamber, the gap between the fiber plate2A and the image pickup element 1A is maintained under a reducedpressure, and a port containing the transparent adhesive is attached tothe aperture 37A, and the pressure is returned to the atmosphericpressure whereby the transparent adhesive 6 is filled into the gap.Thereafter the aperture 37A is sealed with the sealant 38. Then thefiber plate 2A is polished to the area of the image pickup element 1Aand the fiber plate 2A and the image pickup element chip 1A are mutuallyso aligned that the lateral faces thereof coplanarly match (FIG. 31D).The polishing in this step is not chemical polishing utilizing polishingsolution such as potassium hydroxide, ammonia or hydrogen peroxidewater, but is executed by mechanical polishing in order to preventdamage to the image pickup element 1A.

On the fiber plate 2A, a phosphor constituting the wavelength convertingmember 3 of an area same as that of the fiber plate 2A is adhered, or aphosphor of a larger area is adhered and is cut into the size of thefiber plate 2A. An X-ray image pickup unit as shown in FIG. 32E can beobtained in this manner.

An X-ray image pickup apparatus of a large area can be obtained byarranging and bonding plural X-ray image pickup units in such a mannerthat the X-ray receiving faces lie on a same plane.

[Embodiment 15]

FIGS. 33A to 33F are schematic views showing a producing method for thelarge-area fiber plate constituting an embodiment of the presentinvention.

At first plural individual fiber plates 2A are placed on an adheringstage 500, and the bonding material 7 is filled between the fiber plates2A for example with a dispenser. In this operation, the adhering stage500 constitutes a reference plane 53 for the fiber plates 2A (FIG. 33A).

After the setting of the adhesive used as the bonding material 7, thebonded large-area fiber plate 2 is placed on a polishing stage 800 withthe reference plane 53 at the side of a suction hole 54. A polishing pad700 composed for example of felt is mounted on a polishing disk 600(FIG. 33B).

Polishing agent 55 is poured onto the large-area fiber plate 2 and thebonding portion 7 and the polishing disk 600 and the polishing stage 800are rotated in mutually opposite directions under pressurized contact,thereby polishing the individual fiber plates 2A and the bonding portion7 (FIG. 33C). The polishing agent can be so-called slurry containinggrinding particles of silica, celia or alumina family in liquidconsisting of at least one of water and aqueous solution of potassiumhydroxide, ammonia and hydrogen peroxide. In this manner there can beobtained the large-area fiber plate 2 which is so planarized that theindividual fiber plates 2A and the bonding portion 7 lie on a same plane(FIG. 33D).

Then polishing felt 900 is mounted on the external periphery of thepolishing disk 600, and such polishing disk is pressed under rotation tothe lateral face of the large-area fiber plate 2 and the polishing stage800 is moved from the front side to the rear side of the drawing (FIG.33E), thereby polishing the lateral face of the large-area fiber plate2. Subsequently, the polished surface is spin rinsed with rinsing liquid56 supplied for example from a spray nozzle 55, and the polishing stage800 is then rotated at a high speed to dry the fiber plates 2A and thebonding portion 7.

If necessary, the reference plane side may also be polished similarly toobtain the large-area fiber plate with polished light guiding faces.

[Embodiment 16]

FIG. 34 is a plan view showing an embodiment of the radiation imagepickup apparatus of the present invention.

The radiation image pickup apparatus of the present embodiment isprovided with a large-area fiber plate prepared by arranging for exampleten rectangular (60×150 mm) individual fiber plates 2A in two columns byfive rows and a large-area image pickup element prepared by arranging 28rectangular (20×143 mm) image pickup element chips 1A in two columns by14 rows.

The large area fiber plate and the large-area image pickup element areso assembled that the bonding portion 7 between the left and rightindividual fiber plates 2A in FIG. 34 is positioned on the gap betweenthe left and right image pickup element chips 1A. On the other hand, asshown in FIG. 34, the bonding portion 7 between the vertically adjacentindividual fiber plates 2A does not particularly match the gap betweenthe vertically adjacent image pickup element chips 1A. If necessary, itis preferred to select the width of the bonding portion 7 (width ofjoint line) at least betgween the vertically adjacent individual fiberplates 2A smaller than the width of the pixels of the image pickupelement chips 1A.

Also by arranging the image pickup element chips 1A in two columns ortwo rows as shown in FIG. 34, the external connection terminals of allthe image pickup element chips 1A can be positioned not between thechips but on a free end (one of the four sides of the large-area imagepickup element). In this manner it is possible to further reduce the gapbetween the adjacent image pickup element chips.

Among the image pickup apparatuses explained in the foregoing, theapparatus obtained by bonding plural fiber plates 2A with adhesive toobtain a large-size fiber plate, then adhering the base substratemounting plural frame-free image pickup elements on such large-sizefiber plate and combining such assembly with the wavelength convertingmember can provide the following advantages:

1) a large-area detecting apparatus can be prepared;

2) an inexpensive large-area fiber plate can be prepared;

3) a high efficiency of light utilization can be achieved since thefibers are not bent nor inclined;

4) the fiber plate can be prepared with a minimum thickness;

5) the sensor need not be matched with the shape of the fiber plate;

6) the large-area fiber plate can be prepared easily; and

7) wavelength converting member often showing uneven growth, such asalkali metal halide can be satisfactorily grown, so that the obtainedimage provides satisfactory image quality with reduced unevenness.

Based on these advantages, there can be provided an X-ray image pickupapparatus which is capable of providing moving X-ray image, excellent inimage quality, thin, highly reliable and having a large image inputarea. In addition the apparatus is inexpensive.

[Radiation Image Pickup System]

In the following there will be explained a radiation image pickup systemutilizing the image pickup apparatus of the foregoing embodiments.

FIG. 35 is a schematic view showing the concept of a non-destructivetesting system provided with an X-ray image pickup apparatus of theforegoing embodiments.

In FIG. 35, there are shown an X-ray image pickup apparatus 1000 of theforegoing embodiments, an object 2000 of the non-destructive testing,for example an article to be incorporated in an electric equipment, amicrofocus X-ray generator 3000 constituting a radiation source forirradiating the object 2000 with X-ray, an image processing apparatus6000 for processing the signal from the X-ray image pickup apparatus1000, a monitor 4000 for displaying an image processed by the imageprocessing apparatus 6000, and a controller 5000 for controlling theimage processing apparatus 6000 and the monitor 4000.

In the non-destructive testing system shown in FIG. 35, the object 2000to be tested is irradiated by the X-ray generated by the microfocusX-ray generator 3000, and the defect inside the object 2000 is outputtedthrough the X-ray image pickup apparatus 1000 to the image processingapparatus 6000, which processes the image signals of the peripheralpixels of each of the aforementioned image pickup element 1, eventuallywith dark signal correction, to display an image on the monitor 4000.

The image displayed on the monitor 4000 can be subjected for example toimage enlargement or reduction or density control under the instructionof the controller 5000. Through the image displayed on the monitor 4000,the defect inside the object 2000 can be inspected. If no defect isfound in the object 2000, it is considered satisfactory and is used forassembling in the electrical equipment. If a defect is found in theobject 2000, it is identified damaged and is removed from themanufacturing line.

FIG. 36 is a schematic view showing the concept of an X-ray diagnosticsystem provided with an X-ray image pickup apparatus of the foregoingembodiments.

In FIG. 36, there are shown a bed provided with an X-ray image pickupapparatus 1000, an X-ray generator 7000 constituting a radiation sourcefor irradiating an object 2000 with X-ray, an image processor 8000 forprocessing the signal from the X-ray image pickup apparatus 1000 andcontrolling the irradiation time of X-ray from the X-ray generator 7000,and a monitor 4000 for displaying an image processed by the imageprocessor 8000. In FIG. 36, components equivalent to those in FIG. 35are represented by corresponding numbers.

In the X-ray diagnostic system shown in FIG. 36, the X-ray generator7000 generates X-ray according to the instruction from the imageprocessor 8000 to irradiate the object 2000 on the bend, whereby theRoentgen information of the object 2000 is outputted through the X-rayimage pickup apparatus 1000 to the image processor 8000, which processesthe image signals of the peripheral pixels of each of the aforementionedimage pickup element 1, eventually with dark signal correction, to storean image in an unrepresented memory or to display an image on themonitor 4000.

The image displayed on the monitor 4000 can be subjected for example toimage enlargement or reduction or density control under the instructionof the image processor 8000. Through the image displayed on the monitor4000, the doctor diagnoses the object 2000.

The information of the object, after the diagnosis by the doctor, may berecorded for example in a floppy disk, by recording means provided inthis system.

In the foregoing embodiments, there have been explained cases ofutilizing X-ray, but the present invention is likewise applicable toother radiations such as α-ray, β-ray or γ-ray. Also the light is anelectromagnetic wave of a wavelength range detectable by the pixel andincludes visible light. The present invention is furthermore applicableto a converting apparatus for converting an electromagnetic wave,including radiation, into an electrical signal.

What is claimed is:
 1. A fiber plate formed by arranging in a mutuallyadjacent manner a plurality of individual fiber plates of a samethickness so as to provide a light guiding plane larger in area than thelight guiding plane of each of said individual fiber plates, wherein:each of said individual fiber plates is composed of a group of opticalfibers having mutually parallel axes; lateral faces of said adjacentplurality of individual fiber plates are mutually bonded at a bondingportion so that the axes of the optical fibers thereof become mutuallyparallel; and, said bonding portion is a radiation intercepting bondingportion.
 2. A fiber plate according to claim 1, wherein the axes of saidoptical fibers are parallel or inclined to a line normal to said lightguiding plane.
 3. A fiber plate according to claim 1, wherein saidlateral faces are mutually bonded by at least either of an adhesivematerial or a metal.
 4. A radiation image pickup apparatus comprising afiber plate according to claim 1.